Spread & rest over intersection and unions

src/compiler/checker.ts

@@ -3054,7 +3054,15 @@ namespace ts {
         }
 
         function getRestType(source: Type, properties: PropertyName[], symbol: Symbol): Type {
-            Debug.assert(!!(source.flags & TypeFlags.Object), "Rest types only support object types right now.");
+            source = filterType(source, t => !(t.flags & TypeFlags.Nullable));
+            if (source.flags & TypeFlags.Never) {
+                return emptyObjectType;
+            }
+
+            if (source.flags & TypeFlags.Union) {
+                return mapType(source, t => getRestType(t, properties, symbol));
+            }
+
             const members = createMap<Symbol>();
             const names = createMap<true>();
             for (const name of properties) {
@@ -3095,7 +3103,7 @@ namespace ts {
             let type: Type;
             if (pattern.kind === SyntaxKind.ObjectBindingPattern) {
                 if (declaration.dotDotDotToken) {
-                    if (!(parentType.flags & TypeFlags.Object)) {
+                    if (!isValidSpreadType(parentType)) {
                         error(declaration, Diagnostics.Rest_types_may_only_be_created_from_object_types);
                         return unknownType;
                     }
@@ -6102,11 +6110,25 @@ namespace ts {
          * this function should be called in a left folding style, with left = previous result of getSpreadType
          * and right = the new element to be spread.
          */
-        function getSpreadType(left: Type, right: Type, isFromObjectLiteral: boolean): ResolvedType | IntrinsicType {
-            Debug.assert(!!(left.flags & (TypeFlags.Object | TypeFlags.Any)) && !!(right.flags & (TypeFlags.Object | TypeFlags.Any)), "Only object types may be spread.");
+        function getSpreadType(left: Type, right: Type, isFromObjectLiteral: boolean): Type  {
             if (left.flags & TypeFlags.Any || right.flags & TypeFlags.Any) {
                 return anyType;
             }
+            left = filterType(left, t => !(t.flags & TypeFlags.Nullable));
+            if (left.flags & TypeFlags.Never) {
+                return right;
+            }
+            right = filterType(right, t => !(t.flags & TypeFlags.Nullable));
+            if (right.flags & TypeFlags.Never) {
+                return left;
+            }
+            if (left.flags & TypeFlags.Union) {
+                return mapType(left, t => getSpreadType(t, right, isFromObjectLiteral));
+            }
+            if (right.flags & TypeFlags.Union) {
+                return mapType(right, t => getSpreadType(left, t, isFromObjectLiteral));
+            }
+
             const members = createMap<Symbol>();
             const skippedPrivateMembers = createMap<boolean>();
             let stringIndexInfo: IndexInfo;
@@ -11438,7 +11460,7 @@ namespace ts {
                         typeFlags = 0;
                     }
                     const type = checkExpression((memberDecl as SpreadAssignment).expression);
-                    if (!(type.flags & (TypeFlags.Object | TypeFlags.Any))) {
+                    if (!isValidSpreadType(type)) {
                         error(memberDecl, Diagnostics.Spread_types_may_only_be_created_from_object_types);
                         return unknownType;
                     }
@@ -11516,6 +11538,12 @@ namespace ts {
             }
        }
 
+        function isValidSpreadType(type: Type): boolean {
+            return !!(type.flags & (TypeFlags.Any | TypeFlags.Null | TypeFlags.Undefined) ||
+                type.flags & TypeFlags.Object && !isGenericMappedType(type) ||
+                type.flags & TypeFlags.UnionOrIntersection && !forEach((<UnionOrIntersectionType>type).types, t => !isValidSpreadType(t)));
+        }
+
         function checkJsxSelfClosingElement(node: JsxSelfClosingElement) {
             checkJsxOpeningLikeElement(node);
             return jsxElementType || anyType;

src/compiler/transformers/destructuring.ts

@@ -459,7 +459,7 @@ namespace ts {
                 var t = {};
                 for (var p in s) if (Object.prototype.hasOwnProperty.call(s, p) && e.indexOf(p) < 0)
                     t[p] = s[p];
-                if (typeof Object.getOwnPropertySymbols === "function")
+                if (s != null && typeof Object.getOwnPropertySymbols === "function")
                     for (var i = 0, p = Object.getOwnPropertySymbols(s); i < p.length; i++) if (e.indexOf(p[i]) < 0)
                         t[p[i]] = s[p[i]];
                 return t;

tests/baselines/reference/objectRest.js

@@ -43,7 +43,7 @@ var __rest = (this && this.__rest) || function (s, e) {
     var t = {};
     for (var p in s) if (Object.prototype.hasOwnProperty.call(s, p) && e.indexOf(p) < 0)
         t[p] = s[p];
-    if (typeof Object.getOwnPropertySymbols === "function")
+    if (s != null && typeof Object.getOwnPropertySymbols === "function")
         for (var i = 0, p = Object.getOwnPropertySymbols(s); i < p.length; i++) if (e.indexOf(p[i]) < 0)
             t[p[i]] = s[p[i]];
     return t;

tests/baselines/reference/objectRestAssignment.js

@@ -19,7 +19,7 @@ var __rest = (this && this.__rest) || function (s, e) {
     var t = {};
     for (var p in s) if (Object.prototype.hasOwnProperty.call(s, p) && e.indexOf(p) < 0)
         t[p] = s[p];
-    if (typeof Object.getOwnPropertySymbols === "function")
+    if (s != null && typeof Object.getOwnPropertySymbols === "function")
         for (var i = 0, p = Object.getOwnPropertySymbols(s); i < p.length; i++) if (e.indexOf(p[i]) < 0)
             t[p[i]] = s[p[i]];
     return t;

tests/baselines/reference/objectRestForOf.js

@@ -27,7 +27,7 @@ var __rest = (this && this.__rest) || function (s, e) {
     var t = {};
     for (var p in s) if (Object.prototype.hasOwnProperty.call(s, p) && e.indexOf(p) < 0)
         t[p] = s[p];
-    if (typeof Object.getOwnPropertySymbols === "function")
+    if (s != null && typeof Object.getOwnPropertySymbols === "function")
         for (var i = 0, p = Object.getOwnPropertySymbols(s); i < p.length; i++) if (e.indexOf(p[i]) < 0)
             t[p[i]] = s[p[i]];
     return t;

tests/baselines/reference/objectRestNegative.js

@@ -23,7 +23,7 @@ var __rest = (this && this.__rest) || function (s, e) {
     var t = {};
     for (var p in s) if (Object.prototype.hasOwnProperty.call(s, p) && e.indexOf(p) < 0)
         t[p] = s[p];
-    if (typeof Object.getOwnPropertySymbols === "function")
+    if (s != null && typeof Object.getOwnPropertySymbols === "function")
         for (var i = 0, p = Object.getOwnPropertySymbols(s); i < p.length; i++) if (e.indexOf(p[i]) < 0)
             t[p[i]] = s[p[i]];
     return t;

tests/baselines/reference/objectRestParameter.js

@@ -22,7 +22,7 @@ var __rest = (this && this.__rest) || function (s, e) {
     var t = {};
     for (var p in s) if (Object.prototype.hasOwnProperty.call(s, p) && e.indexOf(p) < 0)
         t[p] = s[p];
-    if (typeof Object.getOwnPropertySymbols === "function")
+    if (s != null && typeof Object.getOwnPropertySymbols === "function")
         for (var i = 0, p = Object.getOwnPropertySymbols(s); i < p.length; i++) if (e.indexOf(p[i]) < 0)
             t[p[i]] = s[p[i]];
     return t;

tests/baselines/reference/objectSpreadNegative.errors.txt

@@ -7,20 +7,18 @@ tests/cases/conformance/types/spread/objectSpreadNegative.ts(25,1): error TS2322
   Property 's' is missing in type '{ b: boolean; }'.
 tests/cases/conformance/types/spread/objectSpreadNegative.ts(28,36): error TS2300: Duplicate identifier 'b'.
 tests/cases/conformance/types/spread/objectSpreadNegative.ts(28,53): error TS2300: Duplicate identifier 'b'.
-tests/cases/conformance/types/spread/objectSpreadNegative.ts(32,20): error TS2698: Spread types may only be created from object types.
-tests/cases/conformance/types/spread/objectSpreadNegative.ts(33,24): error TS2698: Spread types may only be created from object types.
-tests/cases/conformance/types/spread/objectSpreadNegative.ts(34,19): error TS2698: Spread types may only be created from object types.
-tests/cases/conformance/types/spread/objectSpreadNegative.ts(35,19): error TS2698: Spread types may only be created from object types.
-tests/cases/conformance/types/spread/objectSpreadNegative.ts(37,20): error TS2698: Spread types may only be created from object types.
-tests/cases/conformance/types/spread/objectSpreadNegative.ts(39,19): error TS2698: Spread types may only be created from object types.
-tests/cases/conformance/types/spread/objectSpreadNegative.ts(44,1): error TS2349: Cannot invoke an expression whose type lacks a call signature. Type '{}' has no compatible call signatures.
-tests/cases/conformance/types/spread/objectSpreadNegative.ts(48,12): error TS2339: Property 'b' does not exist on type '{}'.
-tests/cases/conformance/types/spread/objectSpreadNegative.ts(54,9): error TS2339: Property 'm' does not exist on type '{ p: number; }'.
-tests/cases/conformance/types/spread/objectSpreadNegative.ts(58,14): error TS2698: Spread types may only be created from object types.
-tests/cases/conformance/types/spread/objectSpreadNegative.ts(61,14): error TS2698: Spread types may only be created from object types.
+tests/cases/conformance/types/spread/objectSpreadNegative.ts(32,19): error TS2698: Spread types may only be created from object types.
+tests/cases/conformance/types/spread/objectSpreadNegative.ts(33,19): error TS2698: Spread types may only be created from object types.
+tests/cases/conformance/types/spread/objectSpreadNegative.ts(35,20): error TS2698: Spread types may only be created from object types.
+tests/cases/conformance/types/spread/objectSpreadNegative.ts(37,19): error TS2698: Spread types may only be created from object types.
+tests/cases/conformance/types/spread/objectSpreadNegative.ts(42,1): error TS2349: Cannot invoke an expression whose type lacks a call signature. Type '{}' has no compatible call signatures.
+tests/cases/conformance/types/spread/objectSpreadNegative.ts(46,12): error TS2339: Property 'b' does not exist on type '{}'.
+tests/cases/conformance/types/spread/objectSpreadNegative.ts(52,9): error TS2339: Property 'm' does not exist on type '{ p: number; }'.
+tests/cases/conformance/types/spread/objectSpreadNegative.ts(56,14): error TS2698: Spread types may only be created from object types.
+tests/cases/conformance/types/spread/objectSpreadNegative.ts(59,14): error TS2698: Spread types may only be created from object types.
 
 
-==== tests/cases/conformance/types/spread/objectSpreadNegative.ts (17 errors) ====
+==== tests/cases/conformance/types/spread/objectSpreadNegative.ts (15 errors) ====
     let o = { a: 1, b: 'no' }
 
     /// private propagates
@@ -66,13 +64,7 @@ tests/cases/conformance/types/spread/objectSpreadNegative.ts(61,14): error TS269
 !!! error TS2300: Duplicate identifier 'b'.
     let duplicatedSpread = { ...o, ...o }
 
-    // null, undefined and primitives are not allowed
-    let spreadNull = { ...null };
-                       ~~~~~~~
-!!! error TS2698: Spread types may only be created from object types.
-    let spreadUndefind = { ...undefined };
-                           ~~~~~~~~~~~~
-!!! error TS2698: Spread types may only be created from object types.
+    // primitives are not allowed
     let spreadNum = { ...12 };
                       ~~~~~
 !!! error TS2698: Spread types may only be created from object types.

tests/baselines/reference/objectSpreadNegative.js

@@ -29,9 +29,7 @@ spread = b; // error, missing 's'
 let duplicated = { b: 'bad', ...o, b: 'bad', ...o2, b: 'bad' }
 let duplicatedSpread = { ...o, ...o }
 
-// null, undefined and primitives are not allowed
-let spreadNull = { ...null };
-let spreadUndefind = { ...undefined };
+// primitives are not allowed
 let spreadNum = { ...12 };
 let spreadSum = { ...1 + 1 };
 spreadSum.toFixed(); // error, no methods from number
@@ -108,9 +106,7 @@ spread = b; // error, missing 's'
 // literal repeats are not allowed, but spread repeats are fine
 var duplicated = __assign({ b: 'bad' }, o, { b: 'bad' }, o2, { b: 'bad' });
 var duplicatedSpread = __assign({}, o, o);
-// null, undefined and primitives are not allowed
-var spreadNull = __assign({}, null);
-var spreadUndefind = __assign({}, undefined);
+// primitives are not allowed
 var spreadNum = __assign({}, 12);
 var spreadSum = __assign({}, 1 + 1);
 spreadSum.toFixed(); // error, no methods from number

tests/baselines/reference/restIntersection.js

@@ -0,0 +1,20 @@
+//// [restIntersection.ts]
+var intersection: { x: number, y: number } & { w: string, z: string };
+
+var rest1: { y: number, w: string, z: string };
+var {x, ...rest1 } = intersection;
+
+
+//// [restIntersection.js]
+var __rest = (this && this.__rest) || function (s, e) {
+    var t = {};
+    for (var p in s) if (Object.prototype.hasOwnProperty.call(s, p) && e.indexOf(p) < 0)
+        t[p] = s[p];
+    if (s != null && typeof Object.getOwnPropertySymbols === "function")
+        for (var i = 0, p = Object.getOwnPropertySymbols(s); i < p.length; i++) if (e.indexOf(p[i]) < 0)
+            t[p[i]] = s[p[i]];
+    return t;
+};
+var intersection;
+var rest1;
+var x = intersection.x, rest1 = __rest(intersection, ["x"]);

tests/baselines/reference/restIntersection.symbols

@@ -0,0 +1,19 @@
+=== tests/cases/compiler/restIntersection.ts ===
+var intersection: { x: number, y: number } & { w: string, z: string };
+>intersection : Symbol(intersection, Decl(restIntersection.ts, 0, 3))
+>x : Symbol(x, Decl(restIntersection.ts, 0, 19))
+>y : Symbol(y, Decl(restIntersection.ts, 0, 30))
+>w : Symbol(w, Decl(restIntersection.ts, 0, 46))
+>z : Symbol(z, Decl(restIntersection.ts, 0, 57))
+
+var rest1: { y: number, w: string, z: string };
+>rest1 : Symbol(rest1, Decl(restIntersection.ts, 2, 3), Decl(restIntersection.ts, 3, 7))
+>y : Symbol(y, Decl(restIntersection.ts, 2, 12))
+>w : Symbol(w, Decl(restIntersection.ts, 2, 23))
+>z : Symbol(z, Decl(restIntersection.ts, 2, 34))
+
+var {x, ...rest1 } = intersection;
+>x : Symbol(x, Decl(restIntersection.ts, 3, 5))
+>rest1 : Symbol(rest1, Decl(restIntersection.ts, 2, 3), Decl(restIntersection.ts, 3, 7))
+>intersection : Symbol(intersection, Decl(restIntersection.ts, 0, 3))
+

tests/baselines/reference/restIntersection.types

@@ -0,0 +1,19 @@
+=== tests/cases/compiler/restIntersection.ts ===
+var intersection: { x: number, y: number } & { w: string, z: string };
+>intersection : { x: number; y: number; } & { w: string; z: string; }
+>x : number
+>y : number
+>w : string
+>z : string
+
+var rest1: { y: number, w: string, z: string };
+>rest1 : { y: number; w: string; z: string; }
+>y : number
+>w : string
+>z : string
+
+var {x, ...rest1 } = intersection;
+>x : number
+>rest1 : { y: number; w: string; z: string; }
+>intersection : { x: number; y: number; } & { w: string; z: string; }
+

tests/baselines/reference/restInvalidArgumentType.errors.txt

@@ -0,0 +1,104 @@
+tests/cases/compiler/restInvalidArgumentType.ts(31,13): error TS2700: Rest types may only be created from object types.
+tests/cases/compiler/restInvalidArgumentType.ts(33,13): error TS2700: Rest types may only be created from object types.
+tests/cases/compiler/restInvalidArgumentType.ts(35,13): error TS2700: Rest types may only be created from object types.
+tests/cases/compiler/restInvalidArgumentType.ts(36,13): error TS2700: Rest types may only be created from object types.
+tests/cases/compiler/restInvalidArgumentType.ts(38,13): error TS2700: Rest types may only be created from object types.
+tests/cases/compiler/restInvalidArgumentType.ts(41,13): error TS2700: Rest types may only be created from object types.
+tests/cases/compiler/restInvalidArgumentType.ts(42,13): error TS2700: Rest types may only be created from object types.
+tests/cases/compiler/restInvalidArgumentType.ts(44,13): error TS2700: Rest types may only be created from object types.
+tests/cases/compiler/restInvalidArgumentType.ts(45,13): error TS2700: Rest types may only be created from object types.
+tests/cases/compiler/restInvalidArgumentType.ts(47,13): error TS2700: Rest types may only be created from object types.
+tests/cases/compiler/restInvalidArgumentType.ts(48,13): error TS2700: Rest types may only be created from object types.
+tests/cases/compiler/restInvalidArgumentType.ts(55,13): error TS2700: Rest types may only be created from object types.
+tests/cases/compiler/restInvalidArgumentType.ts(56,13): error TS2700: Rest types may only be created from object types.
+tests/cases/compiler/restInvalidArgumentType.ts(58,13): error TS2700: Rest types may only be created from object types.
+
+
+==== tests/cases/compiler/restInvalidArgumentType.ts (14 errors) ====
+    enum E { v1, v2 };
+
+    function f<T extends { b: string }>(p1: T, p2: T[]) {
+        var t: T;
+
+        var i: T["b"];
+        var k: keyof T;
+
+        var mapped_generic: {[P in keyof T]: T[P]};
+        var mapped: {[P in "b"]: T[P]};
+
+        var union_generic: T | { a: number };
+        var union_primitive: { a: number } | number;
+
+        var intersection_generic: T & { a: number };
+        var intersection_premitive: { a: number } | string;
+
+        var num: number;
+        var str: number;
+
+        var u: undefined;
+        var n: null;
+
+        var a: any;
+
+        var literal_string: "string";
+        var literal_number: 42;
+
+        var e: E;
+
+        var {...r1} = p1;   // Error, generic type paramterre
+                ~~
+!!! error TS2700: Rest types may only be created from object types.
+        var {...r2} = p2;   // OK
+        var {...r3} = t;   // Error, generic type paramter
+                ~~
+!!! error TS2700: Rest types may only be created from object types.
+
+        var {...r4} = i;   // Error, index access
+                ~~
+!!! error TS2700: Rest types may only be created from object types.
+        var {...r5} = k;   // Error, index
+                ~~
+!!! error TS2700: Rest types may only be created from object types.
+
+        var {...r6} = mapped_generic; // Error, generic mapped object type
+                ~~
+!!! error TS2700: Rest types may only be created from object types.
+        var {...r7} = mapped;  // OK, non-generic mapped type
+
+        var {...r8} = union_generic;  // Error, union with generic type parameter
+                ~~
+!!! error TS2700: Rest types may only be created from object types.
+        var {...r9} = union_primitive;  // Error, union with generic type parameter
+                ~~
+!!! error TS2700: Rest types may only be created from object types.
+
+        var {...r10} = intersection_generic;  // Error, intersection with generic type parameter
+                ~~~
+!!! error TS2700: Rest types may only be created from object types.
+        var {...r11} = intersection_premitive;  // Error, intersection with generic type parameter
+                ~~~
+!!! error TS2700: Rest types may only be created from object types.
+
+        var {...r12} = num;  // Error
+                ~~~
+!!! error TS2700: Rest types may only be created from object types.
+        var {...r13} = str;  // Error
+                ~~~
+!!! error TS2700: Rest types may only be created from object types.
+
+        var {...r14} = u;  // OK
+        var {...r15} = n;  // OK
+
+        var {...r16} = a;  // OK
+
+        var {...r17} = literal_string;  // Error
+                ~~~
+!!! error TS2700: Rest types may only be created from object types.
+        var {...r18} = literal_number;  // Error
+                ~~~
+!!! error TS2700: Rest types may only be created from object types.
+
+        var {...r19} = e;  // Error, enum
+                ~~~
+!!! error TS2700: Rest types may only be created from object types.
+    }